Development of an adjustable-focus ferrogel mirror

摘要

This paper introduces a low-cost adjustable-focus ferrogel mirror developed by incorporating magnetic nanoparticles into the micellar structure of poly[styrene-b-(ethylene-co-butylene)-b-styrene] triblock copolymer and a block-selective solvent. This ferrogel remains homogeneous on exposure to different external magnetic fields. A homebuilt Shack-Hartmann wavefront sensor (SHS) was used to measure and reconstruct the wavefronts and to find the profiles of the deformed ferrogel mirrors under the influence of a magnetic field. The effects of main parameters such as ferrogel composition, magnetic nanoparticles concentration, and magnetic field intensity on the mirror performance were investigated. Ferrogel with a lower solvent loading has a higher Young's modulus and demonstrates a milder curvature in a given magnetic field. Higher concentration of nanoparticles results in smaller focal lengths of the ferrogel mirror. This deformable mirror has a good optical surface finish and has the potential to be used in adjustable optical systems.